Process for upgrading desulfurized naphthas



Dec- 20, 1950 N. L. CARR ET Ax. 2,965,561

PROCESS FOR UPGRADING DESULFURIZED NAPHTHAS Filed Deo. 24, 1956 ATTORNEY number.

Unite .ff

PROCESS Fon UPGRADING nnsULFURrzED NAPHrnAs Filed Dec. 24, 1956, Ser. No. 630,383

4 Claims. (Cl. 208-65) This invention relates to `the production of 'high-.octane gasolines. It is more specifically concerned with the processing of full-boiling-range, virgin, `petroleum distillates having an ASTM end-point of about 400 F. to produce high-quality gasoline motor fuels.

In a refining situation wherein such factors as the high .cost of crude petroleum oils, and upward trends in the quality of gasoline-type motor 'fuels are present, it is `essential, from an economic standpoint, that consideration be given to upgrading the several gasoline components that have inferior performance characteristics. The C2 and heavier, normally gaseous olefins can be polymerized 'or alkylated to produce blending stocks of high octane The virgin naphthafraction containing heptane and higher boiling hydrocarbons, having an end boiling `point of about 400 F., normally is subjected to catalytic reforming to provide an aromatic blending material having an improved octane number. The fuel requirements -of high-output, high-speed, spark-ignited, intera] combus- -tion engines with high compression ratios make it necessary "to refine more selectively the various liquid, hydrocarbon constituents boiling in the gasoline range. Be-

cause n-pentane is an important single component which degrades the octane number of gasolnes, refining processes have been developed for the isomerization of a npentane fraction which is fractionated from a debutanized, full-boiling-range naphtha to produce a high-octane-number, iso-pentane-containing blending stock. The remainder of the fraction containing, inter alia, n-hexane and n-heptane is then converted in conventional catalytic reforming processes. Under optimum operating conditions, some latitude in octane number is available, dependfing upon the degree of severity at which the reforming is carried out. Regardless of the severity of the reforming operation, however, n-hexane and n-heptane fractions are hydrocracked to compounds of lower molecular weight upon being subjected to reforming conditions, with only an insignificant amount being converted to aromatic hydrocarbons. As a compromise process, there has been developed a reforming process of relatively low severity, employing platinumor palladium-containing catalysts, e.g., the U.O.P. Rexforming Process. In this process, the reformate is extracted with a selective solvent, viz, diethylene glycol and water, in which the aromatic and low-boiling, non-aromatic components of the reactor eliiuent are soluble. The soluble, higher-boiling, nonaromatics are recovered for reprocessing. These higher boiling components can be subsequently upgraded by processing this low-octane fraction in a thermal reforming unit, or by recycling it to the catalytic reforming section. High contents of aromatic hydrocarbons in gasolines, however, although desirable from an octane rating aspect, often induce other operational difficulties, such as depreciation of road octane values at high speeds, and at part throttle, O and GJ 45 (60) 84. Accordingly, exces- `sive concentrations of aromatics generally are to be avoided.

It is, therefore, the primary object of this invention to States p,tent N A 2,965,561 Patented Dec. 20, 196,0

grading of virgin naphthascontaining pentanes and higherboiling hydrocarbons and having an end-boiling-point "of about 400 F. naphthas in which the deleterious effect Aon liquid yield due to hydrocracking of the n-hexane and nheptane constituents of the `feed stock is minimized, and a gasoline blending stock having excellent road {performance, and containing a desirable content ofaromatic hydrocarbons, `is produced. This and other objects will be made more apparent from the vfollowing detailed description of this invention.

Figure 1 is a schematic Aflow diagram of a preferred embodiment of the invention. For simplicity and ease `of understanding,` onlyessential major processing equipment and flow lines are shown. Conventional pumps, heat exchangers, tanks,etc., that are not shown are understood to be used throughout whererequired.

According to `this invention, a low-,sulfur Ifeed stock, which is herein termed a full-boiling-range naphtha, viz., a debutanized, petroleum-derived naphtha having an ASTM boiling range of about 90-40|0 F., is initially fractionated to produce a low-boiling fraction consisting `essentially of n-heptane and lighter hydrocarbons, and -a high-boiling, residual fraction containing methylcyclohexane and heavier hydrocarbons. The low-boiling fraction is further separated into isomeric and :normal paraffinic fractions. The branched-chain hydrocarbons `are withdrawn as product and the normal hydrocarbons, containing five through seven carbon atoms per molecule, are subjected to catalytic isomerization in the presence of a preconditioned, refractory, acidic, mixed oxides base-hydrogenation-agent composite isomerization catalyst, prepared in accordance with Norman L. Carrs patent application entitled `Catalysts and Process Serial Number 619,376, filed October 3l, 1956. The reaction eiiiuent 4from the isomerization step is fractionated to separate normal` parafiins from their isomers. The isomeric fractions which are recovered are combined with the isomeric constituents from the fresh feed `to form the finished isomeric Vhydrocarbon-containing blending stock. The higher-boiling, residual fraction is subjected to reforming, over a catalyst containing platinum or palladium, at -a low level of severity to produce a reformate. The reformate then is extracted with a selective solvent `to separate an essentially aromatic extract fraction, and a nonaromatic rafiinate fraction. The aromatic fraction, upon being separated from the solvent, is withdrawn as a finished product. The non-aromatic raffinate fraction is fractionated into a distillate fraction containing n-heptane and lighter hydrocarbons, and a residual fraction containing hydrocarbons heavier than n-heptane. The ydistillate fraction is combined with the feed to the isomerization unit. The residual fraction is recycled to the reformer. The finished isomerization product, containing isomeric compounds originally present in the full-range naphtha and those produced in the isomerization unit, is then blended with the finished aromatics from the reforming unit to form a superior motor fuel.

Referring to Figure 1 for a more detailed description, a high-sulfur, full-boiling-range, naphtha is introduced into the process through line 10. Hydrogen from a suitable source hereinafter described is added through line 11 and the combined feed treated in a conventional catalytic hydrodesulfurization section 12 which preferably contains a cobalt-molybdena catalyst. The reaction effluent leaving the reactor 12 through line 13 contains hydrogen sulfide and is separated from the desulfurized, effluent naphtha in separator 14. The hydrogen sulfide is vented through line 15 for use as fuel or a chemical intermediate in the synthesis of other chemical byproducts. The desulfurized naphtha is transferred through line 16 to a superfractionator comprising fractionator 17 and re- The distillate from reruntowerlS is a sharply Depentanizer 19, de-isopentanizer 23, de-isohexanizer 24, dehexanizer 25, and de-isoheptanizer 26 form a consolidated fractionation system to separate isomeric cornpounds from the straight-chain hydrocarbons. The combined isomers are removed as product through line 27. The predominantly straight-chain hydrocarbons removed `from the systems through lines 28, 29, and 30 are combined in line 31 to provide the liquid feed for the isomerization phase. Anymake-up hydrogen required is introduced through line 32 and purified in the hydrogen purifi- 1 cation system 33 comprising a caustic scrubber and a drier where residual hydrogen sulfide and water are removed. These` streams join the recycle hydrogen introduced V'through line 35 and the combined reactor feed is heated to reaction temperature in heater 34. The heated feed is directed into isomerization reactor 36 by means of line 37. The make-up hydrogen is sufficient in quantity to replace hydrogen lost from the system. The efiiuent v' emitted from reactor 36 is freed of gas in reaction efuent 'separator 38 and depropanized in depropanizer 39. The

bottoms from this tower passes through line 40 for isomer recovery in the consolidated fractionation system hereinbefore described. `Using this technique, straight-chain hydrocarbons containing seven or less carbon atoms are -recycled to extinction in this section of the process.

The combined residues from naphtha fractionator 17 and rerun tower 18, passing through line 22, admix with the recycle hydrogen introduced through line 41. This 'admixure is fed into reforming reactor 21. Effluent leaving the reactor system through line 42 is freed of gas by 'flash separation in separator 43 and the liquid reformate -is transferred through line 44 to be stabilized to a desired "extent in stabilizer 45. In the course of the reforming reac- -ftion there is produced a net excess of hydrogen in sufficient amounts to provide hydrogen for use in the hydrodesul- `furization unit and hydroisomerization process. Dry gas comprising normally gaseous, C3 and lighter hydrocarbons from stabilizer 45 is transferred through line 46 to a fuel 'gas system or other use. Stabilized reformate flows from vstabilizer 45 via line 47 to the aromatic separation section which in this illustrative embodiment is a solvent extraction process where the reformate stream is contacted with `a selective solvent which absorbs the aromatics produced vin the reforming section 21. The aromatic extract leaving extractor 48 by means of line 49 is freed of solvent in stripper tower 50 and the aromatic extract is removed as a finished product via line 5,1. The solvent is recycled .in line' 52-for reuse in extraction tower 50. Raffinate fromextractor 48 passing through line 53, is predominant- .lyparainic and is fractionated in fractionating tower 54 .ftoproduce `a distillate containing n-heptane and lighter hydrocarbons and a residue containing hydrocarbons of eight or more carbon atoms which is transferred by means of line 55 for further fractionation in the consolidated feed preparation fractionation system. The distillate joins the fresh light feed and isomerate to form the charge to depentanizer 19. The residual fraction containing C3 and heavier hydrocarbons is recycled to reformer 21 through line 56. Inthe alternative, fractionator 54 could be omitted and the paraflinic rainate returned to the superfractionator through line 57 for reprocessing. It is to be noted that in related, prior art processes, the .paranic'raffinate from the extractor 48 conventionally would vbezfrecycled in its entirety tothe reforming reactor.

-Incontradistinctiom in theprocessj of this invention this -st'ream is fractionated into aprecise, more readily isomerizedffraction and a precise; more readily reformed fraclowing conditions are employed:

visomeric hydrocarbon constituents.

tion, and these streams are subsequently upgraded in a specificfhighly eic'ientmannen a procedure whichl can be used to advantage in employing the preconditioned isomerization catalyst described above. This catalyst, while effectively functioning to facilitate the isomerization of saturated hydrocarbon, has a particular activity for the isomerization of n-heptane. This separation is accomplished in this invention by usinga separate precision fractionator, such as tower 54, or by returning the total raliinate stream to precision fractionator 17 and rerun tower 18, through line 5, the same end result being obvtained by either means. If this separation is not made, the n-heptane and lighter fraction can be upgraded by reforming only if more severe conditions are employed; then the quality of the other reforming products is adversely affected, as is the yield of reformate. Furthermore, these severe conditions cause the formation of au appreciable quantity of coke on the reforming catalyst which reduces its activity. These problems are avoide by the use of this invention. v

To illustrate the instant invention 1000 b.p.d. ofV a delsulfurized, straight run petroleum naphtha having the following characteristics:

Gravity, API 60 Octane No 50 ASTM boiling range, F 90-400 Sulfur content, wt. percent 0.01

and heavier constituents of the feed. By processing'the low-boiling fraction in the isomerization feed preparation ysystem the isomeric hydrocarbons are substantiallyseparated and recovered. The residual n-pentane and nhexane components are treated in a first isomerization reactor while the n-heptane fraction is isomerized in a second isomerization reactor. In these reactors the fol- The catalyst employed in each reactor is a 10% NiMoO4 on 75 silica-25 alumina. This catalyst is prepared by impregnating a silica-alumina support with an aqueous admixture of ammonium paramolybdate and nickel nitrate. The wetted mass is dried and then calcined at van elevated temperature in the presence of hydrogen.

The activated catalyst is preconditioned by alternately voxidizing and reducing the composite catalyst at a temperature of 775 800f F. Complete details for the preparation of this catalyst are set forth in Norman L. Carrs lcopending application entitled Catalysts and Process, Serial Number 619,404, filed October 31, 1956, now Patent No. 2,917,566. The isomerization effluent is returned to the feed preparation system for recovery of the In processing a feed stock of this nature 584 b.p.d. having a Research Octane Number (clear) of is produced.

The higher-boiling residual fraction containing -the vmethylcyclohexane and heavier constituents is employed as feed stock in a reforming step employing the following conditions and three reactors with requisitel reheating: Y v

Pressure, p.s.i.g ,A ,Y 200-500 -Inlet temperature, I'-`.. v 900-920 Liquid weight houly space velocity .2.0 .H3/hydrocarbon mol "ratio ll .4-6

Employing 0.6 wt. percent platinum on `an aluminum support as the catalyst, having a surface area of 527 (BET) sq./m. gram and an ignition loss at 1500" F. of 8.0 wt. percent (Sinclair-Baker RD-150 Catalyst, Petroleum Processing, October 1953), an 84 liquid vol. percent yield of a reformate having a Research Octane Number (clear) of 89 is obtained. The reformate containing about 50% aromatic hydrocarbons is solventextracted with a solvent admixture of diethylene glycol and water, using a solvent-to-feed ratio of to 1. The extract upon being stripped of solvent by conventional fractional distillation provides 336 b.p.d. of aromatic hydrocarbon blending stock having a Research Octane Number blending value of 116.5. By blending this product `with the somerization product, 884 b.p.d. -of gasoline is produced which, having a Research Octane Number (clear) of 93.9 will have a Research Octane Number (3 cc. of T.E.L.) of 100. The raffinate portion of the reformate is then recycled for reprocessing.

As pointed out above, the reforming phase of the process is carried out in the presence of a reforming catalyst comprising platinum or palladium supported on alumina, or on` a siliceous cracking catalyst. Catalysts of this vtype `are well-known in the prior art and contain about 0.1 to 1.0% by weight of platinum or palladium on alumina or a siliceous cracking catalyst, such as silica-alumina, silica-zirconia, silica-alumina-zirconia, etc. Complete descriptions of such` catalysts are contained in a number of U.S. Patents, e.g., 2,478,916; 2,479,109; 2,550,531; 2,589,189; 2,705,329; and others. If desired the catalyst can have a combined halogen (0.1-8.0 percent of uorine or chlorine based on the support) incorporated therein.

These catalysts can be prepared in accordance with conventional techniques by wetting the selected support with an aqueous solution of chloroplatinic acid or chloropalladic acid, or with a aqueous solution of the ammonium salts of these acids. The impregnated support is dried atabout 210-250 F. and reduced in a hydrogen atmosphere between about 200-950 F. (Cf. I & E Chem. 45, 147, 1953). Operating conditions for carrying out the reforming step are selected for producing optimum results. Accordingly, the following conditions are employed:

The somerization of the low boiling fraction` of the feed stock containing the n-Cq and lighter hydrocarbons, is carried out in the presence of a hydrogenation-cracking catalyst composite of improved eiciency prepared in accordance with copending application of Norman L. Carr, viz., U.S. Patent entitled, Catalyst and process, Serial Number 619,376, filed October 31, 1956, now Patent No. 2,917,565. These catalysts are preconditioned in a certain prescribed manner described in the abovementioned application prior to use'. This technique, in essence, comprises incorporating a minor amount of a hydrogenation component in a refractory, mixed oxides base, composited tolevince acidic properties and hydrocarbon cracking activity, substantially in accordance with conventional catalyst preparation techniques. The freshly prepared, green catalyst is activated in a reducing atmosphere in accordance with the prior art to effect reduction of the hydrogenation component of the catalyst as far as possible under specific conditions. Thereafter, the catalyst is subjected to the additional` activation and conditioning `treatment described `in the above-mentioned application.` In carrying out this preconditioning phase of the catalyst preparation, the composite `catalyst is subjected to an oxidizing atmosphere maintained at a temperature of about 650 F. to 750 F. Following this oxidation, the oxidized catalyst is contacted with hydrogen at the same temperature as that at which the oxidation was carried out to reduce the reducible elements of the composition to their lowest state of valency and produce a composite catalyst of high activity and resistance to degeneration. Catalysts prepared in this manner are those which comprise a refractory, mixed oxides base composited to evince acidic properties and hydrocarbon cracking activity, having incorporated therein 2 to 10% of a hydrogenation component, such as group VIII metals of the iron period oxides of polyvalent metals of groups V, VI and VII and group VIII metal of the Viron period salts of oxyacids of polyvalent metals of gro-ups V, VI, and VII. Specific examples of these hydrogenation cornponents include cobalt, nickel, tungsten, oxide, molybdenum oxide, chromium oxide, manganese oxide, vanadium oxide; and cobalt, and nickel salts of the oxyacids of tungsten, molybdenum, chromium, vanadium, and manganese, e.g., nickel tungstate, cobalt molybdate, nickel molybdate, etc. Suitable refractory, acidic, mixed oxide bases include, but are not limited to, SiO2-Al2O3, SiO2-Zr02, SiO2-TiO2, SiOz-B2O3, AlzOag-ZrOz, AlgOa-BeO, Al2O3-B2O3, SiO2-Cr03, B2O3-TiO2, SO2 AIZO3 ZI`O2, SO2A12O3BO, and acid-treated clays. These mixed oxides, in forming the base, can be either in chemical or physical combination. From a standpoint of activity, it has been found that catalyst carriers, containing 50 to 87% silica and 50 to 13% alumina, having incorporated therein 3 to 5% of the hydrogenation agent, are preferred. To facilitate the description of these catalysts they will be referred to as preconditioned, refractory, acidic mixed oxides basehydrogenation agent composite somerization catalysts" and so designated in the appended claims. u

Operating conditionsu selected for the somerization phase are those best suited for somerization of normal pentane, hexane, and heptane. Accordingly, the following conditions are employed:

As indicated, the net production of hydrogen in the reforming normally suffices to provide the amounts required in the desulfurizing and isomerizing sections. However, if necessary, additional amounts can be introduced in the form of fresh, extraneous hydrogen. Makeup hydrogen should contain not more than` a trace of hydrogen sulfide; otherwise, hydrogen from reforming operations is satisfactory, viz., -90 mol percent H2, remainder dry hydrocarbon gases.

The solvent extraction phase of the invention is preferably carried out using conventional liquid-liquid extraction equipment. The solvent employed has a high solubility for aromatcs combined with good selectivity. It must be stable at the operating temperature employed, and preferably, has a high boiling point to permit the distillation of the aromatic hydrocarbons therefrom. This latter characteristic greatly reduces utility requirements. Specific solvents employed include glycols, polyglycols and acyl derivatives, etc., such as diethylene glycol, triethylene glycol, phenol, nitrobenzene, furfural, Chlorex, and others. In addition, mixedsolvents, such asvthose having the foregoing characteristics, discussed by Kalichevsky, ACS Monograph #76, Reinhold, canalsobe employed. Preferably diethylene and trieth.ylene glycols are employed. In accordance with conventional practice",

it is preferred to employ sufficient amounts of water to permit adjusting the selectivity, solubility, and solvency of the solvent to the optimum for the individual case, and at the same time provide a partial pressure of water vapor such that the aromatics may be recovered by stripping or distillation at moderate temperatures and pressures. Generally, 2.5 to 10 volumes of water per volume of solvent can be used. In carrying out the extraction, a solvent/feed volume ratio of 10 to 30 to 1 is used, employing extraction temperatures in the range of 110 to 130 F. Time of contacting should be suicient for essentially equilibrium conditions, and if necessary, pluralstage extraction should be used. Selection of optimum conditions will depend upon the characteristics of the reformate being treated and can readily be determined experimentally. (Vide U.S. Patent 2,770,664.) Depend- Aing upon design requirements, the use of other aromaticrecovering techniques such as adsorption by silica gel or other similar adsorbents, followed by fractional desorption; extractive distillation, azeotropic distillation, etc., can be used to effect the aromatics separation and recycling of the paraflnic fraction.

Feed stocks treated in the process of this invention are debutanized, full-boiling-range, virgin, petroleum naphthas having an ASTM boiling range of about 90 to 400 F. Stocks which are particularly adaptable for processing are those stocks which have a relatively high n-heptane content of about 1 to 1.8 vol. percent of crude. Because this hydrocarbon has a zero octane number, even the presence of small amounts in a gasoline has a deleterious effect on the performance characteristics of the gasoline. Naphthas derived from crudes such as certain Texas, Wyoming and Oklahoma crudes, are relatively high in n-heptane. The process, however, can be used in the processing of naphthas from Mid-Continent, Middle Eastern, and other similar crudes, when, in the processing scheme, n-heptane is produced in the reforming phase. If the full-boiling-range, virgin naphthas have a total sulfur content of less than about 0.003 wt. percent they can be processed without being desulfurized. In the event desulfurization is needed, conventional vapor-phase desulfurization in the presence of such catalysts as bauxite, clay, cobalt molybdate, etc., can be employed. Because of the hydrogen available, hydrodesulfurization employing catalysts such as cobalt, nickel, or iron molybdate, suldes, and chromites, either alone or supported on alumina, silica, zinc oxide, or chromium oxide is preferred. For general discussions relative to operating conditions, reference is made to U.S. Patents 2,325,034; 2,369,432: 2,417,308, and others.

From the foregoing description of this invention it will be noted that excellent versatility and flexibility in operations allow the control of product quality and quantity in an'economically optimum manner for a wide variety of market conditions. In addition, this process provides a higher octane-yield result than can be obtained by reforming conventional reforming stocks and blending virgin light naphtha with the reformate, or reforming plus isomerization with no isomerization of the paraflinic constituents of the reformate. By means of this process, motor fuel having low sensitivity can be produced. Under certain processing conditions, an excess of aromatics is produced which provides a by-product of aromtics, as for the production of petrochemicals. Additional advantages obtain frorn the use of a low-severity reforming phaseV such as longer catalyst life, non-regenerative-type processing, less loss to dry gas, etc. Relatively severe reforming conditions which can be employed to produce a fuel of suiciently high octane number but these adversely affect the quality of thefuel in other respects, such as its effect upon engine cleanliness. These severe conditions result in a product containing aromatic, relatively high-boiling ends which markedly contribute to a dirty engine, principally as Vcrankcase oil contamination. thereforming,section of thisprocess is conducted under comparatively mild conditions, noted above, heavy aromatic ends are at a minimum in the finished aromatics product, and the motor fuel blends made from the two products of this process, viz., isomer product and aromatic product, do not cause excessive crankcase oil contamination. Y

It is evident that various modications of thisA process can be made by those skilled in the art without departing from the scope of this invention. The foregoing examples and embodiments are illustrative and non-limiting and the invention is limited only as defined in the following claims.

We claim:

l. A process for producing a gasoline motor fuel having enhanced road performance characteristics which comprises fractionating a desulfurized, virgin petroleum naphtha boiling between about and 400 F. into a low-boiling fraction consisting essentially of n-Cq and lower-boiling hydrocarbons present in said naphtha, and a consecutive high-boiling fraction containing substantially all of the hydrocarbons present in said naphtha having a boiling point higher than n-Cq, separating the normal hydrocarbon constituents from the branched chain, hydrocarbon constituents of said low-boiling fraction, isomerizing said normal hydrocarbon constituents in an isomerization zone in the presence of hydrogen and a composite catalyst prepared by impregnating a refractory, acidic, mixed oxides base with a hydrogenation agent, and preconditioned by reduction, followed by oxidation at 650-750 F., and reduction with hydrogen at 650-750 F., employing the following reaction conditions:

Range Pressure, p.s.i.g 180-1000 Temperature, F 600-750 Liquid volume hourly space velocity 0.1-2.0 Hz/hydrocarbon mol ratio 0.1-4.5

to produce an isomerization effluent rich in branchedchain, saturated hydrocarbons, and recovering the branched-chain hydrocarbons from said isomerization efuent; catalytically reforming said high-boiling fraction in a reforming zone in the presence of hydrogen and a catalyst consisting essentially of a noble metal selected from the group consisting of platinum and palladium supported on a suitable carrier at a temperature of 900-920 F., under reforming conditions to produce a reformed reaction eflluent, solvent extracting said reformed effluent to produce a parainic fraction and an aromatic fraction,

fractionating said parainic fraction to produce a distillate fraction consisting essentially of n-Cq and lower-boiling hydrocarbons and a residual fraction containing hydrocarbons boiling above n-Cq, recycling said residual fraction to said reforming zone, fractionating said distillate fraction to separate the normal hydrocarbon constituents thereof for treatment in said isomerization zone, and recovering the branched-chain hydrocarbons constituents from said distillate fraction, and blending said branchedchain hydrocarbon constituents from said low-boiling fraction, said isomerization eluent, and said distillate fraction with said aromatic fraction to produce a high octane number gasoline.

2. A process in accordance with claim 1 in which said noble metal is platinum supported on a carrier selected from the group consisting of silica-alumina, and alumina.

3. A process in accordance with claim 1 in which said preconditioned isomerization catalyst is NiMoO4t supported on silica-alumina.

4. A process in accordance with claim 1 in which the isomerization catalyst consists essentially of 8-15% reduced nickel molybdate on silica-alumina, the reforming catalyst consists essentially of G01-1.0% platinum on alumina, and the solvent extraction of a reformed efucnt is carried out using a selective solvent selected from the group consisting of diethylene glycol and triethylene References Cited in the file of this patent UNITED STATES PATENTS 2,443,607 Everng Iune 22, 1948 2,650,906 Engel et al. Sept. 1, 1953 2,687,307 Hendricks Aug. 24, 1954 10 Hartley Oct. 12, 1954 Hemminger et al Dec. 21, 1954 McKinley et al. Sept. 20, 1955 McKinley et al Sept. 11, 1956 Haensel July 16, 1957 FOREIGN PATENTS canada oct. 21, 1952 UNTTTD STATES PATENT oTTicE CERTIFICATIGN 0F CORRECTION Patent No"a 2,965H56l December 2Ox1 lQQWMi corrected belowo Column 5g line 3, for "soga/m., read msq.m/ mig line 59q .for "process" read u Process q column 6s lines 13 and l5 for Hgroup"U each occurrence, read um Group m; same column 6 lines 14 and lot? for "groups"l each occurrencei read Groups uw; column 7g line 50, after "2,369,432; insert; m 23392579; ma

Signed and sealed his 23rd day of May 1961or (SEAL) Attest:

ERNEST W. SWDER DAVID L. LADD Attesting Officer Commissioner of Patents 

1. A PROCESS FOR PRODUCING A GASOLINE MOTOR FUEL HAVING ENHANCED ROAD PERFORMANCE CHARACTERISTICS WHICH COMPRISES FRACTIONATING A DESULFURIZED, VIRGIN PETROLEUM NAPHTHA BOILING BETWEEN ABOUT 90* AND 400*F. INTO A LOW-BOILING FRACTION CONSISTING ESSENTIALLY OF N-C7 AND LOWER-BOILING HYDROCARBONS PRESENT IN SAID NAPHTHA, AND A CONSECUTIVE HIGH-BOILING FRACTION CONTAINING SUBSTANTIALLY ALL THE HYDROCARBONS PRESENT IN SAID NAPHTHA HAVING A BOILING POINT HIGHER THAN N-C7, SEPARATING THE NORMAL HYDROCARBON CONSTITUENTS FROM THE BRANCHED CHAIN, HYDROCARBON CONSTITUENTS OF SAID LOW-BOILING FRACTION, ISOMERIZING SAID NORMAL HYDROCARBON CONSTITUENTS IN AN ISOMERIZATION ZONE IN THE PRESENCE OF HYDROGEN AND A COMPOSITE CATALYST PREPARED BY IMPREGNATING A REFRACTORY, ACIDIC, MIXED OXIDES BASE WITH A HYDROGENATION AGENT, AND PRECONDITIONED BY REDUCTION, FOLLOWED BY OXIDATION AT 650*-750*F., AND REDUCTION WITH HYDROGEN AT 650*-750* F., EMPLOYING THE FOLLOWING REACTION CONDITIONS: TO PRODUCE AN ISOMERIZATION EFFLUENT RICH IN BRANCHEDCHAIN, SATURATED HYDROCARBONS, AND RECOVERING THE BRANCHED-CHAIN HYDROCARBONS FROM SAID ISOMERIZATION EFFLUENT, CATALYTICALLY REFORMING SAID HIGH-BOILING FRACTION IN A REFORMING ZONE IN THE PRESENCE OF HYDROGEN AND A CATALYST CONSISTING ESSENTIALLY OF A NOBLE METAL SELECTED FROM THE GROUP CONSISTING OF PLATINUM AND PALLADIUM SUPPORTED ON A SUITABLE CARRIER AT A TEMPERATURE OF 900*-920* F., UNDER REFORMING CONDITIONS TO PRODUCE A REFORMED REACTION EFFLUENT, SOLVENT EXTRACTING SAID REFORMED EFFLUENT TO PRODUCE A PARAFFINIC FRACTION AND AN AROMATIC FRACTION, FRACTIONATING SAID PARAFFINIC FRACTION TO PRODUCE A DISTILLATE FRACTION CONSISTING ESSENTIALLY OF N-C7 AND LOWER-BOILING HYDROCARBONS AND RESIDUAL FRACTION CONTAINING HYDROCARBONS BOILING ABOVE N-C7, RECYCLING SAID RESIDUAL FRACTION TO SAID REFORMING ZONE, FRACTIONATING SAID DISTILLATE FRACTION TO SEPARATE THE NORMAL HYDROCABON CONSTITUENTS THEREOF FOR TREATMENT IN SAID ISOMERIZATION ZONE, AND RECOVERING THE BRANCHED-CHAIN HYDROCARBONS CONSTITUENTS FROM SAID DISTILLATE FRACTION, AND BLENDING SAID BRANCHEDCHAIN HYDROCARBON CONSTITUENTS FROM SAID LOW-BOILING FRACTION, SAID ISOMERIZATION EFFLUENT, AND SAID DISTILLATE FRACTION WITH SAID AROMATIVE FRACTION TO PRODUCE A HIGH OCTANE NUMBER GASOLINE. 